3D-printed tissue-simulating phantoms for near-infrared fluorescence imaging of rheumatoid diseases.

Significance: Fluorescence imaging of rheumatoid diseases with indocyanine green (ICG) is an emerging technique with unique potential for diagnosis and therapy. Device characterization, monitoring of the performance, and further developments of the technique require tissue-equivalent fluorescent phantoms of high stability with appropriate anatomical shapes.

Aim: Our investigations aim at the development of a three-dimensional (3D) printing technique to fabricate hand and finger models with appropriate optical properties in the near-infrared spectral range.

Heterobifunctional Dyes: Highly Fluorescent Linkers Based on Cyanine Dyes.

Herein, we present a new synthetic route to cyanine-based heterobifunctional dyes and their application as fluorescent linkers between polymers and biomolecules. The synthesized compounds, designed in the visible spectral range, are equipped with two different reactive groups for highly selective conjugation under physiological conditions. By applying indolenine precursors with functionalized benzenes, we achieved water-soluble asymmetric cyanine dyes bearing maleimido and -hydroxysuccinimidyl functionalities in a three-step synthesis.

Responsive Contrast Agents: Synthesis and Characterization of a Tunable Series of pH-Sensitive Near-Infrared Pentamethines.

The demand for responsive dyes in optical imaging is high to achieve a better signal-to-noise ratio and, more specifically, to visualize acidic compartments of the endocytic pathway. Herein, we present a new synthetic route, with a step-by-step synthesis of water-soluble pH-sensitive cyanine dyes exhibiting p values in the region of physiological pH, as confirmed by absorption and fluorescence spectra. Moreover, modification of p values was achieved by two different substitution patterns, creating tunable pH-sensitive dyes.

Terahertz direct-contact refractometer/spectrometer.

A method for terahertz (THz) reflection spectroscopy is presented that utilizes direct contact between the backside of the pulsed emitter and the sample. Changes in the complex reflectivity of the emitter-sample interface are used to measure the spectrum. This method is especially useful for spectroscopy of liquid samples and soft materials.